HOMEWORK

2. HOMEWORK • Labs due – 18 February 2010. NO EXCUSES!!! • Excretion, 4 Bones, blind spot test, pupil & light test, flower, coconut seed, continuous variation • After these 4 labs to do (including seedling lab) • TEST - 18 February 2010 DON’T FORGET!! • Read chapters 26 to 28 in Atwaroo-Ali for 23 & 25 february 2010 for discussion.

3. 10 minute Powerpoint presentations by 4 groups due on 22nd February 2010 (Chap 24 in Atwaroo-Ali) on diseases: • Diabetes (physiological) • Hypertension (physiological) • Malaria (pathogenic) • Physiological, social and economic effects of drug abuse (alcohol included) • I will do AIDS, immunisation & role of blood in defending the body

4. INFO FOR PRESENTATIONS • Diabetes & hypertension: • Definition for term physiological disease • Role of diet & exercise in controlling these diseases • Organs/systems involved • Symptoms & Treatment • Malaria: • Definition for term pathogenic disease • Definition for term vector and identify vector for malaria • Life cycle for malaria parasite (include diagrams)

5. Where in the world is it more prevalent? • Identify how malaria is transmitted to host (give definition for host) • Role of vector in transmitting the disease • Symptoms & treatment • Control of malaria & its vector • Drugs: • Give a definition of drug • Present on alcohol, marijuana/cannabis, cocaine, prescription drugs e.g. steroids, caffeine • Long & short-term effects of drug use & their control • Effects on families, employment • Photos • Read page 281 last subheading

6. VARIATION AND SELECTION NATURAL & ARTIFICIAL SELECTION EVOLUTION

7. VARIATION Genetic vs. environmental variation • Genetic variation is caused by differences in the genetic make-up of individuals. It is inherited. These differences maybe obvious or subtle. • Environmental variation – influenced by the environment. E.g. genetically identical plants are usually identical in appearance however there are times when they are influenced by the environment they may look different. • What factors can cause genetically identical plants to look different (phenotype)?

8. Another example identical twins, how can they look different? • Diet • Exercise • Interests/hobbies • Fingerprints • Importance of genetic variation • Ensures survival of a species if there are drastic changes in the environment. • E.g. of wolves in with different hair lengths (Atwaroo-Ali). Long haired wolves adapt better to colder environments, hence survive harsh cold envts & reproduce vs. short-haired wolves which don’t survive well.

9. EVOLUTION • When a species has changed over a long period of time we say that it has evolved. Evolution is thought to bring about new species.

10. NATURAL SELECTION • It’s the mechanism of evolution by which new species arise. • It allows different forms of a species to survive in different areas. • Over time, these different forms become different & may become different species. • If the environment changes & the species is unable to adapt it may go extinct. • Charles Darwin coined the term natural selection from his observations in the Galapagos Islands.

11. He made several observations: • Organisms produce more offspring than needed to replace them e.g. salmon releases 5M eggs/yr • Despite over-reproduction, stable, established populations of organisms remain the same size e.g. seas are not over-populated with salmon • Members of the same species are not identical – living things vary. • He made 2 important deductions/conclusions: • From 1st two observations he concluded – struggle for existence. Many offspring produced, yet pop’n stays the same size. There must be competition for resources thus many must die.

12. From the 3rd observation he concluded that if some offspring survive they must be adapted or best suited to the environment & reproduce. Less suited individuals die or produce fewer or no young. This is called survival of the fittest. • NOTE: better suited organisms able to reproduce & pass on their genes to their offspring. Those less suited to the environment produce less numbers.

13. EVIDENCE OF NATURAL SELECTION • The theory of natural selection proposes that some factor in the environment ‘selects’ which forms of a species will survive to reproduce under those conditions. • Any evidence of natural selection must show that: • There is variation w/in the species • Changing conditions in the environment (a selection pressure) favours one particular form of the species (which has a selective advantage) • The frequency of the favoured form increases (it is selected for) under these conditions (survival of the fittest) • The frequency of the less well adapted form decreases under these conditions (it is selected against) • The changes are not due to any other factor

14. Examples of natural selection in Atwaroo-Ali • Long necks in giraffes – it is thought that giraffes originally had short necks. Due to limited supply of food at lower levels the giraffes had to reach food high above the ground hence their long necks

15. Another e.g. antibiotic resistance in bacteria. Antibiotics are used to fight against or eliminate certain bacteria. Bacteria not killed develop resistance to antibiotics. • Classic e.g. peppered moth (Bistonbetularia) in England. Two forms of moth: greyish white w/ dark markings (peppered) & dark moth. • Most were peppered type. By 1895, 98% were dark type. What caused the changed? • The peppered variety found mainly in countryside since they were camouflaged with the lichen covered trees & rocks. Hence, the predators couldn’t see them and eat them

16. Pollution from industrialisation produce soot which blackened the trunks and made the peppered moths (lighter ones) stand out against the trunks. Now easy target for predators which killed them. • Hence, nos of peppered variety decreased while darker variety increased in nos. • Nowadays, less pollution – more peppered variety.

18. Table showing evidence of peppered moth as evidence for natural selection

19. Yet another e.g. sickle cell anaemia & malaria • SCA caused by mutant allele. Condition can be fatal for homozygous individuals. • Heterozygous carriers show no symptoms of the disease, although 50% of HB in RBC. However, they have an important benefit. They are more resistant to malaria. • The Anopheles mosquito carries the disease. The malarial parasite spends part of its life cycle in RBCs. • When the parasite is in the fragile RBC, the RBCs burst before the parasite can develop causing parasite to die. Hence life cycle is broken. • Many persons in Africa have SCA

20. NEW SPECIES FORMATION • As environments change, so do selection pressures which affect the survival of species. When pop’ns adapt to new envtal conditions a new species may be formed - SPECIATION. • It can occur when members of species becomes isolated possibly by mountains or bodies of water as in the case of islands. • E.g. Darwin’s finches. He noticed several different species of finches. He concluded that the islands were colonised by a few individuals which evolved to have different ecological niches. • Caribbean also has examples of speciation as seen in the different species of parrots. • NOTE: a species is a group of organisms which are similar to each other & can interbreed.

21. ARTIFICIAL SELECTION • Process by which plants & animals used by humans in areas such as agriculture, horticulture, leisure have been obtained from wild organisms/varieties. • Different from natural selection because humans selects traits that are useful to them & thus allowed to pass on traits to offspring. • Human choice of traits and not environmental factors that provides selection pressure

22. Plants & animals are bred for more than just food but for medicines research into spare-part surgery & the action of drugs (like lab rats) • Humans perform artificial selection to obtain plants & animals with desirable traits such as: • High yields e.g. corn, rice • Improved quality - beef • Reduced production costs • Faster growth rates • Greater resistance to disease – paw paw

23. WHAT FARMERS/HUMANS SELECT FOR IN PLANTS & ANIMALS

24. Since WW II, artificial insemination (AI) has become widely available. • Bulls with desirable features are kept in special places. Their semen is diluted, frozen & stored for purchase to inseminate cows. • Allows for mass distribution of sperm

25. Use of chemicals such as growth hormones & steroids used to enhance or quicken growth & development of animals used for food • Negative consequences due to this e.g. mad-cow disease • The Caribbean has many examples of artificial selection w.r.t. cattle. • Cattle from temperate lands have good meat & milk but couldn’t stand high tropical temperatures • Thus, cattle farmers in Caribbean developed new breeds to withstand harsh conditions

26. Developed Jamaica Red Poll & Jamaica Hope • Buffalypso in T&T

28. TECHNOLOGY & GENETICS • Biotechnology – refers to the way we use plant or animal cells & micro-organisms to produce substances that are useful to us. • Another definition – the science which involves the harnessing & exploitation of biological processes, systems & organisms (mainly micro-organisms) in manufacturing industries. • Biotechnology used for many years: use of fungi to make cheese; bacteria to make vinegar; yeast – bread, beer & wine; lactic acid was used in ancient times to preserve milk to make yoghurt. • Genetic engineering is a form of biotechnology

29. Genetic engineering is the process of changing the genetic structure of living cells in a laboratory. The DNA inside these cells is changed to synthesise/make different proteins. • The aim of GE is to remove a desirable gene from one organism and place it in another organism so its characteristics are expressed in the host organism. • An organism which receives genes from another is called transgenic (genetically modified) organism.

30. A gene is a section of one strand of DNA molecule that codes for the production of protein. • Each sequence of 3 base in DNA strand codes for one AA • Different genes produce different proteins because each has a unique sequence of bases that codes for a unique sequence of AAs – results in a unique protein. Role of DNA in protein synthesis protein DNA mRNA Travels out of nucleus into cytoplasm; at ribosome, tRNA brings AAs in correct order One gene copied

31. mRNA – RNA translated into protein. Called this because it carries genetic message from DNA to ribosomes. • tRNA – transfer RNA

32. The protein that is produced could be: • An enzyme that controls a particular rxn inside a cell or in the digestive system • A structural protein like keratin in hair, collagen in skin or one of the many proteins found in membranes of cells • A hormone • A protein with a specific function such as Hb or an antibody

33. Producing recombinant DNA is the basis of gene technology or GE. • A section of DNA (a gene) is snipped out of the DNA of one species & inserted into the DNA of another. • This new DNA is called recombinant DNA (rDNA) since the DNA from 2 different organisms has been recombined. • Organism with new DNA – transgenic • Transgenic organism can now manufacture the protein its new gene codes for e.g. bacterium that codes for insulin production. • Plasmid – smaller circular pieces of DNA

34. Benefits of GE: • Development of high performance food crops that grow quickly with less fertiliser. This eases pressure on food supplies resulting from growing human pop’n. • Development of disease resistance in crop plants – reduce need for pesticides

35. GE & FOOD PRODUCTION • Scientists use GE to isolate desirable genes & insert them into crop plants. • The bacterium Agrobacterium tumefaciens (Ti) – ideal cell for introducing desirable genes into host cells. • A plant is infected with modified Ti & plant produces a cancerous growth/tumour called a ‘crown gall’. • Cells in the gall each contain the engineered gene

36. Plantlets can be cultured from the small pieces of tissue (explants) cut from the gall. • Plantlets are genetically identical, forming a clone. • Each one carries the engineered gene & is therefore genetically modified (GM). • The GM plantlets are transferred to the soil where they grow to a mature crop – resistant to herbicides.

38. Examples of GE in food production: • Developing genes – inserted into plants them resistant to insect pests. • Improving animals by manipulating embryos. This includes: producing transgenic animals – used to produce useful proteins & medicines; transplanting embryos into surrogate mothers to conserve rare breeds & prevent extinctions • See other examples in Atwaroo-Ali pg 263

39. GE & MEDICINE • Human insulin is manufactured in bacteria as a result of GE. • It was previously obtained from cows & pigs • Now produced by inserting the human gene that codes for insulin into bacteria, allowing them to grow, multiply & produce insulin. • Human insulin is separated, purified & produced on a large scale & used by 1000s of diabetics

41. Other genetically engineered hormones include human growth hormone & calcitonin (which controls the absorption of Ca into bones) • Using human genes to produce hormones helps to prevent harmful side effects of using products from animal tissues. • It also reduces the use of animals for medical research. • GE – used to produce antibodies that maybe useful in the fight against cancer, to develop safer vaccines against diseases like hepatitis B from viruses

42. Also used to treat hereditary diseases such as cystic fibrosis. • CF affects one in every 2500 babies. Caused by a recessive allele which makes mucus in lungs thick & sticky. • Bacteria becomes trapped in mucus & causes infections, leads to early death. • Only treatment was daily physiotherapy to clear mucus in lungs. • Test trials done where sufferers inhale sprays with bacteria containing normal allele. Bacteria transfers these onto cells in the lungs causing them to make runny mucus.

43. Gene therapy – new development in GE • Aims to control diseases caused by faulty genes e.g. SCA • Normal genes are added to patient’s genetic make-up so person doesn’t develop the disease.

44. ISSUES ON GE • Read pg 265 • People see GMOs (genetically modified organisms) as unnatural, & concerned that creating transgenic plants & animals carry some risk to human & animal health & the environment. • One concern – large colonies of bacteria & viruses which may escape into environment

46. Ethical & moral implications: • People feel it is unethical to interfere with natural God-given characteristics in human babies but feel it is ethical to carry out research on animals if it will cure diseases

47. REFERENCES • **Simulation http://www.techapps.net/interactives/pepperMoths.swf • http://sisu.typepad.com/sisu/pepperedmothslichen.jpg • http://www.biology-online.org/2/11_natural_selection.htm • http://www.natureinstitute.org/pub/ic/ic10/giraffe.htm • http://www.whyevolution.com/giraffe.html • ***Moth http://www.millerandlevine.com/km/evol/Moths/moths.html • http://biology.clc.uc.edu/Courses/Bio106/nat-sel.htm • http://sickle.bwh.harvard.edu/malaria_sickle.html • http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gnd&part=anemiasicklecell